Patients with epilepsy have to take medication over prolonged periods in order to control the risk of seizures, leading to high treatment costs. The availability of generic alternatives to innovator drugs is therefore an attractive option for healthcare providers.

However, some reports have found adverse consequences after a switch from branded to generic AEDs. As a result, the UK medical journal The Lancet, has urged, ‘We should err on the side of caution and ensure that AEDs are excluded from any sweeping policies that promote automatic generic substitution’ [1].

The question is, are such doubts valid?

A commentary in the journal Clinical Pharmacology & Therapeutics explains the issues involved [2], and suggests that AEDs may have been misrepresented in terms of safety. Where dosing is concerned, individual tablets of the same medication, whether brand-name or generic, can vary in the amount of active ingredient absorbed by the patient. Yet the onset of seizures in patients following fluctuations between tablets of the same brand is less likely to be reported than if this occurs following generic substitution.

Furthermore, both branded and generic products can vary in quality, depending on where they were manufactured, which could have adverse effects.

Professor Moore and co-authors highlight an observational study showing that prescription refilling itself is associated with an increased risk of seizure, regardless of whether this involved refilling with branded products, a switch to a generic alternative, or from generic back to brand name originator. It may be that prescription refilling can upset a patient’s routine, delay medication, and hence the level of systemically active drug [3, 4].

Other studies are beginning to add to the debate, but as Professor Moore and co-authors suggest, more adequately controlled and powered clinical trials and meta-analyses are required to enable scientifically sound decisions to be made over the safety of generic substitution for the treatment of epilepsy [5].

Related article

Bioequivalence testing for generics

References
1.  Antiepileptic drugs: the drawbacks of generic substitution. Lancet Neurol. 2010 Mar;9(3):227. doi:10.1016/S1474-4422(10)70044-2
2.  Moore N, Berdai D, Begaud B. Are generic drugs really inferior medicines? Clinical Pharmacol Ther. 2010;88(3):302-4. doi:10.1038/clpt.2010.168
3.  Gagne JJ, et al. Refilling and switching of antiepileptic drugs and seizure-related events. Clin Pharmacol Ther. 2010;88(3):347-53.
4.  GaBI Online - Generics and Biosimilars Initiative. Switching from a brand-name antiepileptic drug to a generic is not associated with a higher risk of seizures [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2012 Nov 23]. Available from: www.gabionline.net/Generics/Research/Switching-from-a-brand-name-antiepileptic-drug-to-a-generic-is-not-associated-with-a-higher-risk-of-seizures/
5.  Clayton J. Alleviating concerns around generic antiepileptic medications. Generics and Biosimilars Initiative Journal (GaBI Journal). 2013;2(1):49. doi:10.5639/gabij.2013.0201.002

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